10
OPERATION No MA.IE. 144-00
: Characteristics o/ the K L=Jetronic )) electronic
/uel iujectian system.
AIR-FLOW SENSOR ( 1) :
The role of the air-flow sensor is to supply the E.C.U. with a signal proportional in voltage to the quantity of air
drawn in.
With the engine running, the sensor flap is maintained at an angular position determined by the intensity of the-air- ,
flow, against the resistive action of a spiral spring. The resistance to deflection of the sensor flap, produced by the
spiral spring, is calculated so as to compensate for any mechanical friction ( bearings, bushes ) and to limit the
pressure drop at the flap.
The movement of the sensor flap is damped by a blade rigidly attached to it. This damping blade rotates inside a
housing in which it is a close fit. The operating clearance determines the degree of damping. The use of a damping
blade cancels the effects on the angular position of the sensor flap of pressure variation’s in the inlet collector.
A potentiometer, actuated by the sensor flap spindle, transforms movement of the sensor flap into an electrical
circuit which is transtiitted to the E.C.U.. The voltage of the electrical ‘current is inversely proportional to the
amount of air drawn-in.
In order to cancel the effects of any combustion taking place in the inlet manifold, a one-way valve is incorporated
in the sensor flap.
Thanks to a by-pass channel, a small quantity of the air drawn ,in by-passes the sensor flap. This offers the possibility
of determining the air/lfuel mixture at idling speed by’varying the diameter of the by-pass channel, since the air going
through the by-pass is not measured. The switch for the pump ( engine running ) and the air temperature sensor are
located in the air-flow sensor.
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